Jerry Seinfeld more or less answers that question in this video, in which he recently accepted a Clio Award for his work in advertising -- specifically, his work with American Express:

I love advertising because I love lying."

Then:

I think spending your life trying to dupe innocent people out of hard-won earnings to buy useless, low-quality, misrepresented items and services is an excellent use of your energy."

The comedian held court with his audience for a almost five minutes, shaming the business which is heaping praise on him, but doing so with his trademark wit so that no one seems offended (you get the feeling if Ricky Gervais was up there, half the audience would be booing or would have walked out by the time he was done).

He should receive an award for somehow pulling this speech off without a hitch.